1. Technical Field
The present invention relates to an image processing apparatus, a projector, an image processing method, and a computer program.
2. Related Art
When a projector is set to deviate from an ideal positional relation with a screen, distortion occurs in an image projected on the screen. When a surface on which an image is projected is not a plane, distortion also occurs in the projected image. Therefore, it is known that a function for correcting the distortion of the projected image using projective transformation is provided in the projector. Japanese Patent No. 3914891 discloses that a shape of a figure after transformation is calculated using an approximate expression (a parabolic expression) set in advance to correct distortion of a projected image due to a shape of a projection surface of a columnar screen and various parameters (variable values) necessary for image transformation and optical correction such as a variable for transformation in the lateral direction or a variable for transformation for the longitudinal direction input from a user interface to transform the approximate expression, an optical center, linearity, amplitude, or a position.
When an image is projected to extend across two surfaces (a “first surface” and a “second surface”) crossing each other at an angle, to form a projected image in a shape easy to see as a whole, it is necessary to apply, with different parameters, distortion correction to a portion projected on the first surface and a portion projected on the second surface in the projected image. When one continuous original image is divided into two portions and the distortion correction is applied to the respective portions with the different parameters in this way, as shown in FIG. 9, deviation sometimes occurs in the image in a portion of a line of intersection of the two surfaces.